Carbonylation of aryl halide



nitc tes act 309,951 Patented Nov. 21, test This invention relates to a new process for the production of carboxylic acids, their esters or salts. In particular it relates to a new process for the production of carboxylic acids, their esters and salts by reaction of halogen hydrocarbons with formates.

It is already known that carboxylic acids are obtained by reacting unsaturated compounds with carbon monoxide and water in the presence of metal carbonyls or carbonyl-forming metals, in particular metals of the iron group.

A further known process consists in leading halogenated hydrocarbons with carbon monoxide and steam over active carbon. pumice or silica gel at elevated temperature.

Finally carboxylic acids have already been prepared by the action of Water on the carbonylation products such as are obtainable by the reaction of carbon monoxide with chloro hydrocarbons in the presence of a carbonyl of a metal of the iron group and an ester of a carboxylic acid.

An object of the present invention is to provide a new process for the production of carboxylic acids, their esters or salts which is simpler than the prior processes and is practicable in a technically simple manner. A further object of the invention is a new process for the production of carboxylic acids, their esters and salts in which the danger of corrosion, which is unavoidable in the prior carbonylation processes of chloro hydrocarbons, is obviated.

We have found that these advantages can be obtained and carboxylic acids, their esters or salts are obtained in good yields by treating a halogen hydrocarbon at elevated temperature and under increased pressure with a formate which contains as cation a metal of the first and/or second main group of the periodic system and/or ammonium.

As halogen hydrocarbons there are suitable especially the chlorides or bromides of hydrocarbons of the allphatic, cycloaliphatic,'araliphatic and in particular of the aromatic series. Suitable compounds are particularly chlorides ant kwbrornides of monoand polynuclear aromatic hydrocarbons including those containing condensed rings. For example among the mononuclear aromatic hydrocarbons there may be mentioned chlorbenzene, bromobenzene, bromotoluene, chlorotoluene, and chlorxylenes. AmOng the halogen compounds of polynuclear aromatic hydrocarbons there may be mentioned for examplethose of naphthalene, anthracene and diphenyl. The halogen hydrocarbons may also contain two or more halogen atoms, as for example dichlorobenzene, dibromobenzene, dibromotoluene and dichlorotoluene. Besides the said monoor poly-halogen compounds there may also be used halogen hydrocarbons which besides the halide also contain other radicals, as for example cyano, carboxylic, ester or ether groups. Mixtures of the said halogen hydrocarbons are also suitable.

The reaction is preferably carried out at temperatures between about 100 and 400 C., in particular at 270 to 350 C., and under increased pressure, as for example 5 to 500 atmospheres, particularly 5 to 300 atmospheres, advantageously 100 to 250 atmospheres. For example the reaction may be effected by heating the halogeno hydrocarbon or halogeno hydrocarbon mixture with formates of the metals of the first and/or second main group of the Periodic System, in particular with sodium, potassium or calcium formate, and/or with ammonium tormate, in a closed vessel. The pressure necessary for the reaction thereby being in general automatically set up. If the-necessary pressure is not reached, or if it is desired to work at higher pressures, the desired pressure can be set up by forcing in gases, as for example nitrogen or carbon monoxide. Working under high pressures has the advantage that decomposition of the formates is substantiall or entirely avoided. Corresponding to the course of the reaction reproduced by the following equations for the reaction of dichlorbenzene and sodium formate:

the formate is used in an amount at least equivalent to each gram atom of halogen in the chlorohydrocarbon. It is preferable to use about 1.2 to 2.5 times the calculated amount.

It is not necessary to use the metal or ammonium formates themselves. It is sufficient if these can form during the reaction. For example there may be used instead of the formates, the hydroxides of the alkali or alkaline earth metals or of ammonium and carbon monoxide. For the reaction the hydroxides, of which, besides ammonium hydroxide, in particular sodium, potassium, magnesium, calcium, barium and strontium hydroxide come into question, are used in an amount which is at least sutticient to form the amount of alkali or alkaline earth metal formate or ammonium formate necessary'for the reaction and necessary'according to the above equation. A part of the hydroxide, for ex ample about one to eight tenths of the amount, may also be replaced by carbonates of the metals of the 1st and/ or 2nd main group of the Periodic System or by am monium carbonate.

The reaction may be carried out without or in the presence of substances which accelerate the reaction. Suitable catalysts are for example metal carbonyl compounds, such as the carbonyls of nickel, cobalt, iron, molybdenum and chromium, metal carbonyl hydrides, as for example cobalt carbonyl hydride, or complex compounds, such as Fe(CO.,)Br (R P) Ni(CO) or (R P)Ni(CO) in which R represents a hydrocarbon radical, especially an alkyl group. When Working in the presence of catalysts it is not necessary to add the metal carbonyl compounds as ready-made compounds, but rather they may also be formed during the reaction from their components. Thus for example it is sufficient, when working under a pressure of carbon monoxide, to add the carbonyl-forming metals themselves to the reaction mixture, and the carbon monoxide used may also contain other gases, especially hydrogen. ,Other suitable catalysts are for example metals, such as copper or silver, especially in finely divided form, as well as the halides of copper, silver, nickel, cobalt and iron.

When working in aqueous or alcoholic solution it is necessary, when the formates are formed during the reaction, for example from the alkali hydroxides and carbon monoxide, to use the hydroxy compound in not too small concentration because otherwise the course of the reaction is retarded or entirely stopped. In this case it is therefore preferable to use the hydroxides in a concentration of at least 10% and advantageously 50% or more, as for example up to If it is desired to obtain only the salts instead of the carboxylic acids, this may be achieved in a simple way by adding to the initial mixture also compounds having a basic reaction, as for example oxides, hydroxides, car- 3 bonates or salts of weak organic acids and alkali or alkaline earth metals or ammonia or organic bases, such as alkylamines, pyridine or quinoline, or, when starting from hydroxides instead of formates, by using currespondingly increased amounts of hydroxides. When working'in an alcoholic media for example in the presence of a lower aliphatic alcohol such as methanol, ethanol or propanol the ester of the aromatic carboxylic acids are obtained.

The process may be carried out continuously or discontinuously. It is not necessary to work in corrosionproof apparatus.

The following examples will further illustrate this invention but the invention is not restricted to these examples. The parts, where specified, are parts by weight.

Example 1 147 grams of para-dichlorbenzene and 272 grams of sodium formate are slowly heated in a copper rolling bomb under a carbon monoxide pressure of 50 atmospheres to 320 C., the pressure thereby rising to 110 atmospheres. After 6 hours, the contents-of the autoclave are extracted with benzene. From the extract there are recovered 35 grams of para-dichlorbenzene. The salt-like residue is dissolved in water, 2 grams of terephthalic acid remaining undissolved. The aqueous solution is acidified with hydrochloric acid. The acid mixture of parachlorobenzoic acidand terephthalic acid which separates is filtered off and dried. The total yields amount to 13 grams of para-chlorbenzoic acid and 80 grams of terephthalic acid.

Example 2 250 grams of para-dichlorbenzene are heated with 272 grams of sodium formate and 30 grams of nickel carbonyl in a copper rolling autoclave of 2 litres capacity at 270 to 280 C. under a pressure of 200 atmospheres of carbon monoxide for lhours. It is then allowed to cool and is decompressed. The reaction mixture is extracted with benzene. From the extract 58 grams of unreacted part-dichlorbenzene are recovered by distilling olf the benzene. The residue of the reaction mixture which does not pass into the benzene phase is treated with water and the aqueous solution acidified with hydrochloric acid. The precipitate, which consists of terephthalic acid, is filtered ofl and dried. Besides small amounts of para-chlorbenzoic acid, 20 grams of terephthalic acid are obtained. The part which is insoluble in water is extracted with methanol, whereby upon drying there are obtained as residue another 77 grams of terephthalic acid and 4% of para-chlorbenzoic acid.

Example 3 147 grams of para-dichlorbenzene are heated with 272 grams of sodium formate and 30 grams of nickel carbonyl in a copper rolling autoclave of 2 litres capacity for 10 hours at 270 to 280 C. under 5 atmospheres carbon monoxide pressure. The reaction mixture is worked up in the way described in Example 1. Terephthalic acid is obtained in a yield of 50% of the theoretical yield.

Example 4 147 grams of para-dichlorbenzene, 80 grams of sodium hydroxide and 36 grams of water are charged into a rolling bomb and heated to 310 C. after 120 atmospheres of carbon monoxide have been forced in. The pressure thereby rises to 250 atmospheres and is kept constant for hours by' forcing in carbon monoxide when the pressure falls. The pulverulent product is extracted with water and 14 grams of terephthalic acid are precipitated from the aqueous filtrate by acidification with mineral acid. The residue undissolved in water is treated with benzene, whereby 59 grams of unreacted para-dichlorbenzene pass into solution and 65 grams of terephthalic acid remain uhdissolvcd. The yield amounts to 79% of the theoretical yield (degree of conversion 59.9%

Example 5 para-dichlorbenzene which has not entered into reaction.

The yield of terephthalic acid amounts of 79% of the theoretical yield (conversion 90.5%).

By working under otherwise identical conditions while using 1,440 grams of water, a yield of terephthalic acid of only 1 gram is obtained.

Example 6 74 grams of para-dichlorbenzene, 80 grams of sodium hydroxide and 36 grams of water are charged into a shaking bomb lined with copper and shaken at 310 C. for 20 hours after atmospheres of carbon monoxide have been forced in.

The reaction product is extracted with water and the aqueous solution acidified, whereby 47 grams of terephthalic acid are thrown down as an insoluble precipitate. From the water-insoluble residue there are obtained 10 grams of terephthalic acid and 2 grams of unreacted paradichlorbenzene. The yield of terephthalic acid amounts to 68.8% of the theoretical yield (conversion 98.8%

Example 7 147 grams of para-dichlorbenzene, 40 grams of sodium hydroxide, 160 grams of calcined soda and 108 grams of water are charged into a rolling bomb. After forcing in 100 atmospheres of carbon monoxide, it is heated to ,310" C. and the rolling bomb kept at this temperature for 20 hours. The reaction product is extracted with water and the aqueous solution acidified. 91 grams of terephthalic acid are obtained. From the residue insoluble in water there are recovered 2 grams of terephthalic acid and 1 gram of unreacted paradichlorbenzene. The conversion is practically complete. The yield of terephthalic acid amounts to 56% of the theoretical yield.

Example 8 Example 9 230 parts of para-dibrombenzene, 80 parts of sodium hydroxide and 40 parts of water are charged into a rolling autoclave and, after forcing in atmospheres of carbon monoxide, heated for 28 hours at 310 to 320 C., the pressure thereby rising to 300 atmospheres. The reaction product is extracted with water and the aqueous solution acidified with aqueous hydrogen chloride solution. 44 parts of bromobenzoic acid and 66 parts of terephthalic acid are obtained. The water-insoluble portion (20 parts) consists of para-dibromobenzene.

Example 10 147 parts of ortho-dichlorbe'nzene, 80 parts of sodium hydroxide, 40 parts of water and 10 parts of nickel cardiphenyl together with a formate of an alkali metal at a temperature of from 100 to 400 C. and under a carbon monoxide pressure of from 5 to 500 atmospheres in a diluent, then dissolving the reaction product, after it has been freed from the unreacted halogeno-hydrocarbon, separating the undissolved remaining compounds and acidifying the aqueous solution.

2. A process for the production of benzene dicarboxylic acids and diphenyl dicarboxylic acids which comprises heating a member of the group consisting of dichlorobenzene, dibromobenzene, dichlorodiphenyl, and dibromodiphenyl with at least the equivalent amount of a formate of an alkali metal at a temperature of from to 400 C. and under a carbon monoxide pressure of from to 500 atmospheres, for a period of at least about six hours, then dissolving the reaction product in water after it has been freed from unreacted halogenohydrocarbon, separating the undissolved remaining compounds and acidifying the aqueous solution.

3. A process for the production of benzene dicarboxylic acids and diphenyl dicarboxylic acids which comprises heating a member of the group consisting of dichlorobenzene, dibromobenzene, dichlorodiphenyl, and dibrornodiphenyl together with a formate of an alkali metal at a temperature of from 270 to 350 C. and under a carbon monoxide pressure of from 5 to 500 atmospheres, then dissolving the reaction product in.water after it has been freed from the unreacted halogenohy- Q m e/t) drocarbon, separating the undissolved remaining compounds, and acidifying the aqueous solution.

4. The process claimed in claim 3, wherein the reaction is carried out in the presence of a nickel carbonyl compound.

5. The process claimed in claim 3, wherein the alkali metal formate is formed during the reaction from an alkali hydroxide and carbon monoxide, said hydroxide being present in an aqueous solution having a concentration of at least about hydroxide.

6. The process claimed in claim 3, wherein one tenth to eight tenths of the amount of hydroxide which is necessary for the 'formation of the formates by reaction with carbon monoxide is replaced by the corresponding alkali metal carbonate.

7. A process for the production of benzene dicarboxylic acids which comprises reacting a dihalogenobenzene selected from the group consisting of dichlorobenzene and dibromobenzene with at least the equivalent amount of a formate of an alkali metal at a temperature of to 400 C. and under a carbon monoxide pressure of from 5 to 500 atmospheres, then dissolving the reaction product in water after it has been freed from the unreacted halogeno-hydrocarbon, separating the undissolved remaining compounds and acidifying the acqueous solution.

8. The process as claimed in claim 7 wherein the formate of an alkali metal is formed by the interaction of the corresponding alkali metal hydroxide and carbon monoxide, said hydroxidebeing present in an aqueous solution having a concentration of at least about 50% hydroxide.

9. The process as claimed in claim 7, wherein the formate used is sodium formate.

10. The process according to claim 7, wherein nickel carbonyl is used as a catalyst.

References Cited in the file of this patent UNITED STATES PATENTS 2,013,338 Carpenter Sept. 3, 1935 2,565,461 Bliss et a1 Aug. 28, 1951 2,565,464 Tabet Aug. 28, 1951 2,734,912 Leibu Feb. 14, 1956 UNITED STATES PATENT. OFFICE ERTIFICATE OF CORRECTION Patent No; $069351 November 21, 1961 Hugo T of; a1,

It is hereby certified .that error appears in the above numbered petent'requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 21, for "parrfiz-dichlorbenzene" read para-dichlorbenzen-e column 4:, line 12 for "of",

second occurrerwe Toad "50 Signed and sealed this 15th day of May 1962o (SEAL): Attest:

" ERNEST W. SWIDER I Attes ting Officer DAVID L. LADD Commissioner of Patent 

1. A PROCESS FOR THE PRODUCTION OF BENZENE DICARBOXYLIC ACIDS AND DIPHENYL DICARBOXYLIC ACIDS WHICH COMPRISES HEATING A MEMBER OF THE GROUP CONSISTING OF DICHLOROBENZENE, DIBROMOBENZENE, DICHLORODIPHENYL, AND DIBROMODIPHENYL TOGETHER WITH A FORMATE OF AN ALKALI METAL AT A TEMPERATURE OF FROM 100* TO 400*C. AND UNDER A CARBON MONOXIDE PRESSURE OF FROM 5 TO 500 ATMOSPHERES IN A DILUENT, THEN DISSOLVING THE REACTION PRODUCT, AFTER IT HAS BEEN FREED FROM THE UNREACTED HALOGENO-HYDROCARBON, SEPARATING THE UNDISSOLVED REMAINING COMPOUNDS AND ACIDIFYING THE AQUEOUS SOLUTION. 